1. Field of the Invention
The present invention relates to a method of checking reception of a message and transmitting reception acknowledgment information associated with the received message in a two-way radio communication system in which a plurality of communication terminal devices transmit and receive information to and from each other, and also to a storage medium on which a reception acknowledgment transmission program is stored for use in such a two-way radio communication system. The present invention also relates to a two-way radio communication system and a base station for use in the two-way radio communication system.
2. Discussion of the Background
In most widely-used paging systems or similar systems, a large-zone downstream radio system is employed, in which a message is transmitted in only one direction from a caller's telephone to a recipient's receiving terminal device such as a pager unit. There is no practical two-way radio communication system that allows a caller and a recipient to send and receive a message to and from each other.
Recently, a paging system has been proposed in which a called device sends a message reception acknowledgment signal to a calling device. For example, in the technique disclosed in Japanese Unexamined Patent Publication No. 61-208931, when a user of a pager unit serving as a receiving terminal device receives a message from a caller, if the user of the pager unit presses a particular button of the pager unit, data indicating the status of the called pager is sent to the caller. Japanese Unexamined Patent Publication No. 3-38122 discloses a technique in which when a pager unit receives a calling signal, a beeping sound is generated to inform a called person (user of the pager unit) of arrival of a message and an acknowledgment signal is sent to a caller.
However, the conventional techniques of checking and acknowledging reception of a message are applicable only to a one-way radio communication system in which a message is sent in only one direction from a caller to a recipient, and the techniques cannot be typically employed in a two-way radio communication system in which a message is sent in both directions. Another problem of the conventional techniques of checking and acknowledging reception of a message is that when a base station receives a reception acknowledgment signal sent from a called device, the base station immediately transfers the received acknowledgment signal to a calling device and thus the base station often encounters congestion of various data, which brings about a reduction in processing efficiency in the transmission of messages to called devices.